On Wed, 15 Jun 2022 14:22:18 +0800 Kuan-Ying Lee <Kuan-Ying.Lee@xxxxxxxxxxxx> wrote: > Currently, KASAN describes all invalid-free/double-free bugs as > "double-free or invalid-free". This is ambiguous. > > KASAN should report "double-free" when a double-free is a more > likely cause (the address points to the start of an object) and > report "invalid-free" otherwise [1]. > > [1] https://bugzilla.kernel.org/show_bug.cgi?id=212193 > > ... Could we please have some review of this? Thanks. > > diff --git a/mm/kasan/common.c b/mm/kasan/common.c > index c40c0e7b3b5f..707c3a527fcb 100644 > --- a/mm/kasan/common.c > +++ b/mm/kasan/common.c > @@ -343,7 +343,7 @@ static inline bool ____kasan_slab_free(struct kmem_cache *cache, void *object, > > if (unlikely(nearest_obj(cache, virt_to_slab(object), object) != > object)) { > - kasan_report_invalid_free(tagged_object, ip); > + kasan_report_invalid_free(tagged_object, ip, KASAN_REPORT_INVALID_FREE); > return true; > } > > @@ -352,7 +352,7 @@ static inline bool ____kasan_slab_free(struct kmem_cache *cache, void *object, > return false; > > if (!kasan_byte_accessible(tagged_object)) { > - kasan_report_invalid_free(tagged_object, ip); > + kasan_report_invalid_free(tagged_object, ip, KASAN_REPORT_DOUBLE_FREE); > return true; > } > > @@ -377,12 +377,12 @@ bool __kasan_slab_free(struct kmem_cache *cache, void *object, > static inline bool ____kasan_kfree_large(void *ptr, unsigned long ip) > { > if (ptr != page_address(virt_to_head_page(ptr))) { > - kasan_report_invalid_free(ptr, ip); > + kasan_report_invalid_free(ptr, ip, KASAN_REPORT_INVALID_FREE); > return true; > } > > if (!kasan_byte_accessible(ptr)) { > - kasan_report_invalid_free(ptr, ip); > + kasan_report_invalid_free(ptr, ip, KASAN_REPORT_DOUBLE_FREE); > return true; > } > > diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h > index 610d60d6e5b8..01c03e45acd4 100644 > --- a/mm/kasan/kasan.h > +++ b/mm/kasan/kasan.h > @@ -125,6 +125,7 @@ static inline bool kasan_sync_fault_possible(void) > enum kasan_report_type { > KASAN_REPORT_ACCESS, > KASAN_REPORT_INVALID_FREE, > + KASAN_REPORT_DOUBLE_FREE, > }; > > struct kasan_report_info { > @@ -277,7 +278,7 @@ static inline void kasan_print_address_stack_frame(const void *addr) { } > > bool kasan_report(unsigned long addr, size_t size, > bool is_write, unsigned long ip); > -void kasan_report_invalid_free(void *object, unsigned long ip); > +void kasan_report_invalid_free(void *object, unsigned long ip, enum kasan_report_type type); > > struct page *kasan_addr_to_page(const void *addr); > struct slab *kasan_addr_to_slab(const void *addr); > diff --git a/mm/kasan/report.c b/mm/kasan/report.c > index b341a191651d..fe3f606b3a98 100644 > --- a/mm/kasan/report.c > +++ b/mm/kasan/report.c > @@ -176,8 +176,12 @@ static void end_report(unsigned long *flags, void *addr) > static void print_error_description(struct kasan_report_info *info) > { > if (info->type == KASAN_REPORT_INVALID_FREE) { > - pr_err("BUG: KASAN: double-free or invalid-free in %pS\n", > - (void *)info->ip); > + pr_err("BUG: KASAN: invalid-free in %pS\n", (void *)info->ip); > + return; > + } > + > + if (info->type == KASAN_REPORT_DOUBLE_FREE) { > + pr_err("BUG: KASAN: double-free in %pS\n", (void *)info->ip); > return; > } > > @@ -433,7 +437,7 @@ static void print_report(struct kasan_report_info *info) > } > } > > -void kasan_report_invalid_free(void *ptr, unsigned long ip) > +void kasan_report_invalid_free(void *ptr, unsigned long ip, enum kasan_report_type type) > { > unsigned long flags; > struct kasan_report_info info; > @@ -448,7 +452,7 @@ void kasan_report_invalid_free(void *ptr, unsigned long ip) > > start_report(&flags, true); > > - info.type = KASAN_REPORT_INVALID_FREE; > + info.type = type; > info.access_addr = ptr; > info.first_bad_addr = kasan_reset_tag(ptr); > info.access_size = 0; > -- > 2.18.0 >
